The group of alkali metals comprises chemical elements that can be found in the first group of the periodic table of elements, and is known for its strong exothermic chemical reactivity. It is exactly this reactivity that makes handling of these alkali metals, such as crushing, shredding and other mechanical processing steps, a challenging and risky procedure.
In practice, the alkali metals, which comprise lithium, sodium, potassium, rubidium, caesium and francium, are handled within a protective environment chosen to suppress or control the reaction of the alkali metals with any other substance, such as water, acids and nonmetals. The reactivity of the alkali metals increases from lithium to francium and as pure elements they are usually stored in oil for safety. Examples of handling procedures as described above, can be found within the lithium battery recycling industry.
With atomic number 3, lithium is the first element in group 1 of the periodic table. Lithium metal reacts very readily with many compounds, generating large quantities of energy and often involving fires and explosions. Lithium especially reacts explosively with any water or water vapour available, generating hydrogen gas, which itself is highly explosive.
Batteries are the main power source for a wide variety of electric and electronic equipment. As batteries contain a large array of different chemical and metallurgical substances, the collection of waste batteries for recycling is ever increasing. For many types of these batteries well established recycling technologies are in operation.
Portable lithium batteries are ever more used in consumer, military and professional applications. Collection and recycling of these batteries pose special problems and require dedicated and professional attention to prevent accidents in the logistic chain from the user until the recycling facility, and during the recycling process itself. The types of hazardous and polluting chemical substances which are liberated during the recycling process need special attention too.
Given the chemical properties of lithium, the main recycling technology for portable lithium batteries is very complicated and expensive because of the use of cryogenic technologies in an extremely low temperature environment of liquid nitrogen. Further, cryogenic processes itself may use quite hazardous materials.
Cryogenic recycling processes have been described in U.S. Pat. No. 5,888,463 and U.S. Pat. No. 5,345,033, where the batteries are cooled down to low temperatures after which they are comminuted and the contents are neutralized.
Another known technology is the use of a protective environment of inert gases like helium, argon, krypton, xenon or neon (alternatively even nitrogen is used), as is described in European patent application 613,198. In addition, European patent application EP 1,041,659, mentions the use of a non-oxidizing atmosphere.
These complicated and expensive technologies pay respect to the high reactivity of lithium metal, and the hazardous nature of many of the substances used as electrolytic and cathodic material in these batteries, by directly suppressing an exothermic reaction by means of reducing the internal energy (cryogenic processes) or preventing contact between lithium and its reaction components.
Another disadvantage of the abovementioned dismantling processes, is that they are all very polluting, each in their own way. Note that cryogenic processes consume a lot of energy, and the use of inert gasses requires the first of all purification of these inert gasses which is as well very energy consuming (this again often requires cryogenic processes).
In addition, although these processes provide a means of dismantling the substances, these substances are to be collected first in order to make the process more cost effective. The transportation and storage of these substances provides, in turn, an environmental hazard and requires a lot of preparations.